1) freedom to do otherwise: I am free to do otherwise if, being the same agent, with the same desires and beliefs, and being in the same circumstances, it is possible for me to do or not to do something in the sense that it is not fully causally determined whether or not I do it.

2) freedom of decision: a subtype of freedom to do otherwise. I am free in my decision, if being the same agent, with the same desires and beliefs, and being in the same circumstances, it is possible for me to decide between alternative courses of action in the sense that it is not fully causally determined which way I decide. 1) differs from 2) in that it leaves it undecided in which way it is possible for the agent to do or not to do something.

3) freedom of the will: a subtype of freedom of decision. I act from free will, if I am in the possession of a will, i.e. a specific part or faculty of the soul by means of which I can decide between alternative courses of actions independently of my desires and beliefs [this is "extreme"], in the sense that it is not fully causally determined in which way I decide. 2) differs from 3) in that the latter postulates a specific causally independent faculty or part of the soul which functions as a "decision making faculty."
(Phronesis, p.133)

Bobzien contrasts these radical libertarianisms with what she calls "un-predeterminist" freedom:

4) un-predeterminist freedom: I have un-predeterminist freedom of action/choice if there are no causes prior to my action/choice which determine whether or not I perform/choose a certain course of action, but in the same circumstances, if I have the same desires and beliefs, I would always do/choose the same thing. Un-predeterminist freedom guarantees the agents' autonomy in the sense that nothing except the agents themselves is causally responsible for whether they act, or for which way they decide. Un-predeterminist freedom requires a theory of causation that is not (just) a theory of event-causation (i.e. a theory which considers both causes and effects as events). For instance, un-predeterminist freedom would work with a concept of causality which considers things or objects (material or immaterial) as causes, and events, movements or changes as effects. Such a conception of causation is common in antiquity.
(Phronesis, p.133)

In Bobzien's "un-predeterminist" freedom, there is nothing that causally determines the agent's action, but the agent will always make the same decision in exactly the same circumstances, because the decision is completely consistent with the agent's desires and beliefs (and character and values).

5) freedom from force and compulsion: I am free in my actions/choices in this sense, if I am not externally or internally forced or compelled when I act/choose. This does not preclude that my actions/choices may be fully causally determined by extemal and internal factors.

6) freedom from determination by external causal factors: agents are free from external causal factors in their actions/choices if the same external situation or circumstances will not necessarily always elicit the same (re-)action or choice of different agents, or of the same agent but with different desires or beliefs.

7) freedom from determination by (external and) certain internal causal factors: I am in my actions/choices free from certain intemal factors (e.g. my desires), if having the same such internal factors will not necessarily always elicit in me the same action/choice.
(Determinism and Freedom in Stoic Philosophy, p.278)

In 1967 Epicurus was credited with the discovery of the problem of free will and determinism. Among the contestants were Aristotle and the early Stoics.

Furley merely de-emphasized the direct involvement of the random swerve in volition, as had Bailey before him.

Epicurus emerged victorious, because — so the argument went — Aristotle did not yet have the problem, and the Stoics inherited it from Epicurus. In the same year David Furley published his essay 'Aristotle and Epicurus on Voluntary Action', in which he argued that Epicurus' problem was not the free will problem. In the thirty-odd years since then, a lot has been published about Epicurus on freedom and determinism.

But it has only rarely been questioned whether Epicurus, in one way or another, found himself face to face with some version of the free will problem. In this paper I intend to take up the case for those who have questioned the point, combining a fresh perspective on the debate with a selection of new arguments and a detailed textual analysis of the relevant passages. Let me begin with a brief sketch of the problem of freedom and determinism which Epicurus is widely taken to have been concerned with.

The determinism Epicurus defends himself against is usually understood as causal determinism: every event is fully determined in all its details by preceding causes. These causes are commonly pictured as forming an uninterrupted chain or network, reaching back infinitely into the past, and as governed by an all-embracing set of laws of nature, or as manifestations of such a set of laws of nature.

Freedom to do otherwise, freedom of decision, and extreme freedom of the will Bobzien now labels "two-sided" freedom

On the side of freedom, Epicurus is generally understood to have been concerned with freedom of decision (the freedom to decide whether or not to do some action) or freedom of choice (the freedom to choose between doing and not doing some action) or freedom of the will (where the freedom to will to do something entails the freedom to will not to do it, and vice versa; I call this two-sided freedom of the will). Epicurus is taken to have introduced an indeterminist conception of free decision or free choice or two-sided free will: agents are free in this sense only if they are causally undetermined (or not fully causally determined) in their decision whether or not to act or their choice between alternative courses of action; undetermined, that is, by external and internal causal factors alike. There is assumed to be a gap in the causal chain immediately before, or simultaneously with, the decision or choice, a gap which allows the
coming into being of a spontaneous motion.

In this way every human decision or choice is directly linked with causal indeterminism. The assumption of such indeterminist free decision, free choice, or two-sided free will does not presuppose that one specifies an independent mental faculty, like e.g. a will, and indeed it is not usually assumed that Epicurus' theory involved such a faculty.

The 'free will problem' that Epicurus is assumed to have faced is then roughly as follows: If determinism is true, every decision or choice of an agent between alternative courses of actions is fully determined by preceding causes, and forms part of an uninterrupted causal chain. On the other hand, if an agent has (two-sided) freedom of the will, it seems that the agent's decision or choice must not be fully determined by preceding causes. Hence, it appears, determinism and freedom of the will (freedom of decision, freedom of choice) are incompatible.

I do not believe that Epicurus ever considered a problem along the lines of the one just described. In particular, I am sceptical about the assumption that he shared in a conception of free decision or free choice akin to the one I have sketched. (I also have my doubts that he ever conceived of a determinism characterized by a comprehensive set of laws of nature; but this is a point I only mention in passing.) To avoid misunderstandings, I should stress that I do believe that Epicurus was an indeterminist of sorts — only that he did not advocate indeterminist free decision or indeterminist free choice.

Bobzien is of course right that Epicurus did not think that our decisions were made at random with no regard for our character and values, or for our feelings and desires. This is a straw argument put up by critics of Epicurean philosophy, notably the Stoic Chryssipus and the Academic Skeptic Cicero.

But Bobzien is wrong to suggest that Epicurus did not see a problem between human freedom and the causal determinism of his fellow atomist Democritus, and that Epicurus' atomic swerve was not his proposed solution to that "free will problem (viz, by breaking the causal chain)." Bobzien recognizes that her claim depends on the definiton of free will when she notes that

Whether Epicurus discussed free will depends on what one means by 'free will'. For example, if one intends 'free will' to render Lucretius "libera voluntas," and to mean whatever element of Epicurus' doctrine Lucretius meant to capture by this phrase, then Epicurus evidently was concerned with free will. My concern is only to show that he did not discuss a problem of free will that involves a conception of freedom of decision or choice as adumbrated in the main text. [namely, "extreme" libertarianism in which chance is the direct cause of action.]